Advanced breast cancer: Can bisphosphonates prevent broken bones?

Women with breast cancer that has spread to the bones can reduce their risk of broken bones by taking bisphosphonates. It is not known, though, whether one particular bisphosphonate medication is better than others.

Cancer spreading to the bones is one of the fears with advanced breast cancer. Cancer cells move to the skeleton and start to grow there. This growth weakens the bones so much that it can lead to painful breaks.

Researchers have been testing bisphosphonate drugs in recent years to try to find a way to protect women with advanced breast cancer from broken bones. It is known that these drugs can slow down damaging bone loss.

To assess the benefits and adverse effects of these drugs, researchers from the Cochrane Collaboration, an international research network, gathered and systematically analyzed the treatment results of 21 trials among almost 7,200 women with advanced breast cancer.

Bisphosphonates can slow down damage to bones

Their most important conclusion was that although bisphosphonates cannot completely stop bone damage from cancer, the treatment reduced the number of broken bones. However, it is not possible to judge whether one particular medication is more effective than others. The evidence suggests that these drugs only have a benefit for women in whom cancer has already spread to the bones. It does not seem as though bisphosphonates can prevent cancer spreading to the bones, and they do not appear to lengthen life, either.

Serious adverse effects such as severe nausea, fever or calcium deficiency were uncommon in the trials. When bisphosphonates are used in combination with other cancer drugs there is an increased risk of problems with the jawbone following dental treatment.

The risk of certain, rare fractures is higher, however

The European Medicines Agency (EMA) reported in April 2011 that bisphosphonates can lead to fractures (breaks) of the thigh bone in rare cases. But they increase this risk only for what are called atypical stress fractures. These fractures are caused by long-term overuse of the bone and not by a sudden, severe impact from outside the body. They represent only a small part of all thigh bone fractures. For this reason, the EMA stands by their assessment that the benefit of using bisphosphonates outweighs their risks.

Warnings signs of stress fractures can often be noticed weeks or months ahead of time. Typical symptoms are pain or a feeling of weakness in the affected area. If women who are taking bisphosphonates notice these signs in their thigh, it is important they notify their doctor. Because these fractures can happen on both sides, both legs need to be examined. In most cases that have been examined, the stress fractures only developed after years of taking bisphosphonates.

You can read more about breast cancer here.

Author: German Institute for Quality and Efficiency in Health Care (IQWiG)

(The latest update only contains the EMA recommendation from April 2011. Other information on the advantages and disadvantages of bisphosphonates has not been updated.)

© IQWiG (Institute for Quality and Efficiency in Health Care)